The invention relates to a multi-speed boat transmission.
In conventional,boat transmissions, a fixed propeller is driven by a motor via a transmission having a constant ratio. The consequence of this construction is that the propulsion system can be optimally coordinated only for one operating point.
However, there are often situations in which such constructions have an unfavorable effect: when, e.g. the propulsion system is designed for a final speed as high as possible, the motor is pressed relative to the rotational speed when the boat resistance is increased as a result of weather conditions, cargo, etc. whereby only one part of the total power of the motor is available. Besides, the acceleration properties are poor and the thermal load of the motor is high. This also results in the production of soot.
On the other hand, if the propulsion system is designed for an acceleration as high as possible or for driving with elevated resistance, the nominal rotational speed of the motor under normal conditions is achieved without delivering full power in the process. This has a negative effect on the final speed obtainable.
It thus becomes necessary to optimize the propulsion device so that it is adaptable to different conditions of operation whereby the motor can always work in an optimal rotational speed range.
To that end, a variable-pitch propeller has been proposed. But this solution mechanically requires much expenditure and, consequently, is expensive and unusual in yachts/speed boats. A variable-pitch propeller also has poor efficiency.
DE 196 24 913 A1 discloses a marine propeller system having one motor, one shifting mechanism and one programmable electronic control device with a shifting parameter matrix. The electronic control device monitors the motor load and the revolution rate and produces a control signal which controls the shifting operations. Since this system forms one unit, it is not possible to change over already existing transmissions of the conventional kind mentioned above. On the contrary, new transmissions must be developed according to those requirements.
DE 31 02 556 A1 discloses a two-step transmission for boat propeller systems in which a planetary transmission is used. This transmission has a direct gear with a 1:1 ratio shiftable by a friction clutch for the cruising drive, while for a drive at highest speed a high speed gear is provided which is formed by the planetary transmission and a hydraulic clutch, and gears up the rotational speed.
With this construction, it is not possible to implement any small speed ratio changes for the high-speed range: likewise a simple change of the ratio is not possible. Furthermore, losses occur in the highest speed range.
Therefore, the problem on which this invention is based is to make a power shiftable boat transmission available which, in combination with a fixed propeller or water jet, allows a variable adaptation to different operating conditions.
Accordingly, on an already existing basic transmission, it is proposed to flange mount a separate front-mounted transmission having at least two countershafts wherein the countershafts are distributed around the periphery of the main shaft of the basic transmission in a manner such that no additional forces act upon the main shaft. The front-mounted transmission can be flange mounted on different transmission designs of boat propelling families without having to develop entirely new transmissions, therefore, the possible uses are multiple.
In addition, the front-mounted transmission is modularly built so that it can be coordinated by adapting a few parts to different operating conditions without having to develop new transmissions.
Besides, the stepping-up parts are configured in such a way that, via a provided plug-in system, it is possible to prepare both a gear up and a gear down ratio, with identical parts, but by a different assembly. Moreover, by varying the number of individual stepping-up parts teeth, different ratio ranges can be implemented. Moreover, by varying the number of individual stepping-up parts teeth, different ratio ranges can be implemented.
All this requires only a small assembly expenditure wherein almost arbitrary ratios can be implemented and, in particular, small ratio changes are also possible, unlike in a planetary transmission.
The construction proposed is of reasonable cost, since in most cases only a different assembly of identical parts is needed. It also offers a high measure of flexibility in regard to different requirements.